/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    AttributeValueLiteral.java
 *    Copyright (C) 2003 Peter A. Flach, Nicolas Lachiche
 *
 *    Thanks to Amelie Deltour for porting the original C code to Java
 *    and integrating it into Weka.
 */

package weka.associations.tertius;

import weka.core.Instance;
import weka.core.RevisionUtils;
import weka.associations.Tertius;

/**
 * @author Peter A. Flach
 * @author Nicolas Lachiche
 * @version $Revision: 1.6 $
 */
public class AttributeValueLiteral extends Literal {

	/** for serialization */
	private static final long serialVersionUID = 4077436297281456239L;

	private String m_value;

	private int m_index;

	public AttributeValueLiteral(Predicate predicate, String value, int index,
			int sign, int missing) {

		super(predicate, sign, missing);
		m_value = value;
		m_index = index;
	}

	public boolean satisfies(Instance instance) {

		if (m_index == -1) {
			if (positive()) {
				return instance.isMissing(getPredicate().getIndex());
			} else {
				return !instance.isMissing(getPredicate().getIndex());
			}
		} else if (instance.isMissing(getPredicate().getIndex())) {
			if (positive()) {
				return false;
			} else {
				return m_missing != Tertius.EXPLICIT;
			}
		} else {
			if (positive()) {
				return (instance.value(getPredicate().getIndex()) == m_index);
			} else {
				return (instance.value(getPredicate().getIndex()) != m_index);
			}
		}
	}

	public boolean negationSatisfies(Instance instance) {

		if (m_index == -1) {
			if (positive()) {
				return !instance.isMissing(getPredicate().getIndex());
			} else {
				return instance.isMissing(getPredicate().getIndex());
			}
		} else if (instance.isMissing(getPredicate().getIndex())) {
			if (positive()) {
				return m_missing != Tertius.EXPLICIT;
			} else {
				return false;
			}
		} else {
			if (positive()) {
				return (instance.value(getPredicate().getIndex()) != m_index);
			} else {
				return (instance.value(getPredicate().getIndex()) == m_index);
			}
		}
	}

	public String toString() {

		StringBuffer text = new StringBuffer();
		if (negative()) {
			text.append("not ");
		}
		text.append(getPredicate().toString() + " = " + m_value);
		return text.toString();
	}

	/**
	 * Returns the revision string.
	 * 
	 * @return the revision
	 */
	public String getRevision() {
		return RevisionUtils.extract("$Revision: 1.6 $");
	}
}
